Field of Invention
The present invention relates to a calibration plate for calibrating a plurality of image capturing devices and a method for calibrating a plurality of image capturing devices, and more particularly to a calibration method that adopts calibration patterns and graphically encoded patterns having both regular arrangement and repetitiveness on a calibration plate to calibrate image contents and position relationships of a plurality of image capturing devices.
Related Art
Taiwan Patent Publication No. TW 201018882 discloses a calibration system and a calibration method, in which mainly graphs of a calibration plate at different magnifications and a matrix calibration pattern are used to calibrate image and movement platform of an image capturing device, so as to achieve precision measurement. However, this method is only applicable to the calibration of a single image and is not applicable to the calibration for a plurality of channels or a plurality of image capturing devices.
U.S. Pat. No. 5,978,081 discloses designs of a calibration graph and a calibration plate for use in semiconductor manufacturing, in which it is mainly designed that known matrix dot graph placed opposite are at all image capturing devices, and the positions, orientations and aberration definitions of image capturing devices are calibrated at the same time, thereby enhancing planar visual precision. However, a graphic area needs to be designed for image capturing positions, and therefore the application flexibility is low.
U.S. Pat. No. 6,301,396 discloses a method for calibrating the position and orientation of an image, in which mainly a feature shape of a known graph is used to recognize a orientation and a relative position of the graph, and a similar graph at a known relative position is designed for a plurality of image capturing devices, so as to obtain practical relative positions of the image capturing devices. However, the graphic design thereof is limited, the approximate positions of the image capturing devices need to be known in advance, and the problem such as distortions and aberrations of the image cannot be solved at the same time.
In the prior art, a conventional calibration plate with matrix dot pattern only can be used in the image calibration for a single image capturing device, which is already insufficient for calibrating relative positions and mechanical movement positions of multiple image capturing devices. When a position relationship between image capturing devices needs to be calibrated, an image captured by each image capturing device has to contain the graph of the entire calibration plate, which is not applicable to calibrate large-area and high-definition machine image. The earlier prior art patents have mentioned the calibration of a plurality of image capturing devices, but the design flexibility thereof is low, which is not applicable to the image capturing devices that cannot be predicted or that often need to move The conventional calibration of the image capturing devices lacks the consideration of image calibration for the whole planar space, and no longer satisfied the current fabrication processes in optoelectronics, automated assembly, and machine vision industry.
Therefore, a method for calibrating multiple image capturing devices and a calibration plate using the method need to be provided to solve the foregoing problem.